Charge IS conserved!

The C in CPT is not only a change f charge but also a change of electron <---> positron, and quark <---> antiquark, and ...

The conservation or charge comes from the U(1) gauge symmetry. That is almost obvious if you ignore the mixing with the weak interaction, but after the mix you still have a U(1) gauge symmetry anyway.

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throwaway81523 15 hours ago | parent [-]

I thought that in an expanding universe, mass isn't conserved. I don't see why charge would be conserved in that case.

	▲	caturopath 2 hours ago \| parent [-]
		Mass isn't close to being conserved. If an electron and positron annihilate, they become two massless photons, for example. You don't need to invoke an expanding universe. In an expanding universe, energy isn't conserved. (Unless we do the trick we always do with energy and just define it to be conserved https://youtu.be/lCgKTpIzjRk?t=174 ) I don't know exactly why you think this applies to charge conservation. The U(1) symmetry is where charge conservation comes from and it isn't affected by an expanding universe.